Many states offer legal guardianship forms free online that can be printed and filed with the probate court. The Petition for Appointment of Guardian form is the first step in filing for legal guardianship. An example is available on the California Courts page of the Judicial Branch of California.
There may be unique paper and ink requirements for printed guardianship forms as explained by Pine Tree Legal Assistance. For example, Maine Probate requires natural white paper, rather than bright white and requires that multiple page documents be double-sided. Franklin County Probate Court in Ohio has different forms based on guardianship for an adult or a minor.